This invention relates in general to cooling towers and deals more particularly with a system of vertical louvers which can be installed on a cooling tower for the purpose of totally or partially enclosing the tower to control the flow of air through it.
In a cross flow natural draft evaporative type cooling tower, the water that is to be cooled is delivered to a hot water basin and is allowed to gravitate through an underlying fill toward a cold water basin at the base of the tower. The "fill" is that portion of a cooling tower which represents its primary heat transfer surface, sometimes referred to as "packing". Ambient air flows through the water as it gravitates through the fill, and the water is thereby cooled by a combination of evaporative effects and sensible heat exchange. The ambient air enters the cooling tower through air spaces presented between horizontal louvers or slats mounted on the sides of the tower.
In cold weather climates, it is necessary in the winter at times to control the air flow by closing off some or all of the air spaces in order to control the formation of "unacceptable" ice. "Unacceptable" ice can be categorized as either a significant amount of ice that has formed on the fill, jeopardizing the operation and existence of the heat transfer surface; or excessive ice in a support region which may threaten the tower structure. The potential for ice varies directly with the quantity of air flowing through the tower, and reducing the air flow retards the formation of ice. This can be done by constructing the horizontal slats such that they are pivotal between open and closed positions. However, this makes the louver system much more expensive and, consequently, it is more common for the louvers to be fixed slats which cannot be adjusted to control the air spaces. With a fixed slat arrangement, it is sometimes necessary in cold weather to mount temporary panels on the cooling tower for covering of at least some of the air spaces and often all or most of them. The need to repeatedly install and remove the temporary panels results in significant labor and equipment requirements which add appreciably to the overall cost of operating the cooling tower. In addition, the temporary panels must be stored while not in use and must be repeatedly transported to and from the storage location.